The starting point is declared in each ship's code. In games with same mods enabled, many ships can have different starting point. CC overwrites the three starting ships to start at Tau Ceti, but if you add playership mods you'll have to change the startPos in the code

That seems to be the case. I <think> I have started the game with a Sapphire and started in Tau Ceti. Maybe I changed my mind at the last second. Anyway, the reason the Osaka starts in Eridani is still because that is what is defined in the ship's code.